Preheat oven to 450˚F. Lightly grease a rimmed baking sheet with cooking spray and set aside.

In a large mixing bowl, combine trimmed Brussels sprouts, olive oil, minced garlic, salt, and pepper. Mix until well combined. Transfer Brussels sprouts to the prepared baking sheet, arrange them in a single layer, and bake for 14 minutes, stirring once or twice during cooking.

Drizzle salmon with olive oil, evenly divide and press minced garlic on top of each fillet. Season the salmon with oregano, salt, and pepper.

Remove the baking sheet from the oven and move the Brussels sprouts around to make room for the salmon fillets. Place the salmon on the baking sheet and bake for 10 to 12 minutes, or until cooked through. Larger fillets will need a couple more minutes to cook through.

Remove from oven. Let the salmon and veggies stand for a few minutes and serve.